Analytical Solution for Steady State Seepage in Foundation Pits in Permeable Anisotropic Soils Considering Retaining Wall Thickness

An analytical study was conducted on the two-dimensional steady state seepage in a foundation pit in a permeable anisotropic soil layer considering the thickness of the retaining wall support. According to the symmetry, with the half section of the foundation pit taken, the surrounding soil layer was divided into five regular zones. The permeable anisotropic soil layer was transformed into an equivalent isotropic soil layer by using the coordinate transformation. For each zone, an explicit analytical solution for the two-dimensional steady state seepage field, the water pressure on the retaining wall and the exit gradient at the bottom of the pit was derived by using the superposition method and the method of separation of variables. Compared with the conformal mapping and integral transformation methods, the seepage field calculation results of the solution of this paper were continuous and singularity-free. The head distribution of the pit and the water pressure distribution on both sides of the retaining wall were in good agreement with the numerical analysis, showing the correctness and superiority of the analytical solution in this paper. The comparative analysis between the results of the wall water pressure calculation solved in this paper and those of retaining wall water pressure calculation obtained by different calculation methods shows that the influence of the thickness of the retaining wall d and the vertical to horizontal permeability coefficient ratio a on the water pressure on the retaining wall cannot be ignored. An analysis was made on the influence of a and d of suspended retaining wall on the water pressure at the bottom of the retaining wall and the exit gradient. With the increase of a and <i, the water pressure at the bottom of the retaining wall outside the pit increases while the water pressure at the bottom of the retaining wall inside the pit decreases. With the decrease of a and d, the exit gradient at the bottom of the pit increases continuously. When a and d are small, the safety of the calculated exit gradient in the one-dimensional seepage case is low. In addition, as a and d decrease, the difference between the calculation results and the analytical solution of this paper increases. © 2024 Science Press. All rights reserved.